JPH02125431A - Semiconductor device - Google Patents

Abstract

PURPOSE:To alleviate shadowing effect, to improve coverage, and to prevent electromigration, stress migration by applying a film of high melting point metal such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum and silicide compounds of them to a lower layer of interconnections of second or after layers. CONSTITUTION:In order to form interconnections of first layer, titanium 203 is first sputtered to a whole surface, titanium nitride 204 is then sputtered, Al-Si 205 is eventually sputtered, and a part necessary for interconnection remains in a photoetching step. An oxide film 206 is formed on the whole surface as an insulating film with the interconnection of a second layer. Further, a hole part is opened in a photoetching step. Eventually, in order to form interconnection of second layer, titanium, molybdenum, tungsten, tantalum, cobalt, platinum, and further silicide compounds 207 of them are sputtered, aluminum alloy 208 is then sputtered, and the part necessary for tie interconnection remains in the photoetching step.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multilayer wiring structure of a semiconductor device.

[Prior art 1] A conventional semiconductor device and its wiring structure have a structure as shown in Fig. 4, and the AI wiring of 405 and 406 has a two-layer wiring structure with an upper layer of aluminum alloy and a lower layer of titanium nitride. It has become. At this time, resistance increased due to the titanium nitride in the hole portion, a shadowing effect appeared during spucking, and furthermore, Si in the aluminum alloy grew, making it difficult to miniaturize.

To explain this in accordance with the conventional process, first, an oxide film (S i O 2 ) 402 is formed on the entire surface of the St substrate 401 and a contact portion is opened by photo-etching. A material for the first layer wiring 403 is sputtered thereon and photoetched. Furthermore, an oxide film (SiO,) 404 is formed on the entire surface as an insulating film with the second layer wiring, and the hole portion is opened by photo-etching. Finally, in order to form a second layer of interconnection, titanium nitride 405 is sputtered, aluminum alloy 406 is further sputtered, and photoetching is performed using six or more conventional steps.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, as contacts become finer, AI is applied to the steps of the contacts during Al sputtering.
There are problems in that it causes a shadowing effect in which the particles are not applied uniformly, and that the resistance of the hole portion is also unstable.

Therefore, the present invention aims to solve these problems.
The purpose is to replace titanium nitride with high-melting point metals such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum, or silicide compounds of these as shown in Figure 1 107 to eliminate shadowing. Reduces effects and improves coverage.

Furthermore, even if the AI wiring is broken, current flows from the lower layer, thereby providing a wiring that is strong against electromigration and stress migration.

[Means for Solving the Problems] The semiconductor device of the present invention has wiring in the second and higher layers, the upper layer of which is an aluminum alloy, the lower layer of which is a high melting point metal such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum, or any of these metals. The upper layer is titanium nitride, the middle layer is an aluminum alloy, and the lower layer is made of high melting point metals such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum, and silicide compounds of these. It is characterized by three-layer wiring.

[Function J] According to the above structure of the present invention, titanium, molybdenum, tungsten, tankle,
By attaching a film of high melting point metals such as cobalt, platinum, and their silicide compounds, AI can move more easily on the film during Al sputtering, making it easier to uniformly adhere to the hole area, and reducing the shadowing effect. . Furthermore, the grains of At in the upper layer become large, making it possible to provide wiring that is strong in preventing electromigration.

[Example 1] A semiconductor device of the present invention has the structure shown in FIG.

101 is an St substrate, 102 is an oxide film of silicon dioxide, 1
03, 104, and 105 are the first layer wiring, 103 is titanium, 104 is titanium nitride, and 105 is aluminum alloy.

106 is silicon dioxide of an oxide film, 107 and 108 are second layer wiring, 107 is titanium, molybdenum, tungsten, Kuntal, cobalt, platinum, and silicide compounds thereof, and 108 is an aluminum alloy.

Details will be explained below with reference to FIG. 2 while following the steps.

First, an oxide film (SiO,) 20 is placed on the entire surface of the Si substrate 201.
form 2. (FIG. 2(a)) Further, a contact portion is opened by a photo-etching process. (FIG. 2(b)) Next, in order to form the first layer of wiring, titanium 203 is first sputtered on the entire surface, firstly titanium nitride 204 is sputtered, and finally Al-5i 205 is sputtered. A photo-etch process leaves the necessary parts for the wiring. (Figure 2 (C)) Next, an oxide film (
Sin2) 206 is formed. (FIG. 2(d)) Furthermore, the hole portion is opened by a photo-etching process. (
(Fig. 2(e)) Finally, in order to form the second layer of wiring, titanium, molybdenum, and tungsten are first applied to the entire surface.

Kuntal, cobalt, platinum, and their silicide compounds 207 are sputtered, and then aluminum alloy 208 is sputtered, and the portions necessary for wiring are left through a photo-etching process (FIG. 2(f)). Compared to conventional semiconductor devices, the semiconductor device of the present invention completed through the process has a hot portion made of high-melting point metals such as titanium, molybdenum, tungsten, quantal, cobalt, platinum, and silicide compounds of these, and aluminum. Since the wiring is made of two layers of alloy, the aluminum alloy easily moves on the high melting point metal during Al sputtering, making it easier for the aluminum alloy to uniformly adhere to the hole portion.

Furthermore, the growth of silicon in the aluminum alloy can be suppressed, and the grains of AI in the upper layer aluminum alloy become larger, making it resistant to electromigration.

Further, as shown in FIG. 3, the three-layer wiring formed by sputtering titanium nitride 301 after AI sputtering is more effective in preventing stress migration and electromigration than the two-layer wiring. Furthermore, titanium nitride is effective in preventing halation as an antireflection film.

Further, in order to maintain the resistance as before, it is preferable to set the film thickness ratio between the aluminum alloy and the lower layer to 1/10 or less.

Finally, the present invention has similar effects on wiring in the third and higher layers.

[Effects of the Invention] According to the present invention described above, compared to the conventional two-layer wiring,
The shadowing effect can be alleviated, and coverage can therefore be improved. Furthermore, the growth of silicon in the aluminum alloy can be suppressed, and the grains of Al in the upper layer aluminum alloy become large, making it resistant to electromigration.

Furthermore, even if the Al wiring is broken, current will flow from the bottom layer if it is a two-layer wiring, or from the bottom and top layers if it is a three-layer wiring, which is effective in preventing electromigration and stress migration. is effective in preventing halation as an anti-reflection film.

[Brief explanation of the drawing]

1 and 3 are main sectional views showing a semiconductor device of the present invention. FIGS. 2(a) to 2(f) are cross-sectional views of the manufacturing process of the semiconductor device of the present invention. FIG. 4 is a main cross-sectional view showing a conventional semiconductor device. 101...Si substrate 102 ・ 103 ・ 104 ・ 105 ・ 106 ・ 107 ・ l 08 ・ 201 ・ 202 ・ 203 ・ 204 ・ 205 ・ 206 ・ 207 ・ 208 ・ 301 ・ 401 ・ 402 ・ ・Silicon dioxide・Titanium・Nitride Titanium, first layer wiring, silicon dioxide, titanium, molybdenum. High melting point metals such as n, second layer wiring, Si substrate, silicon dioxide, titanium, titanium nitride, first layer wiring, silicon dioxide, high melting point metals such as titanium, molybdenum, n, etc., second layer Wiring・Titanium nitride・Si substrate・Silicon dioxide Tungsten Tungste 403 ・ 404 ・ 405 ・ 406 ・・・First layer wiring・・Silicon dioxide・Titanium nitride・・Second layer wiring

Claims (1)

[Claims] In a semiconductor device having multiple wiring layers, the second and higher wiring layers have an upper layer made of an aluminum alloy and a lower layer made of high melting point metals such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum, and silicide compounds thereof. Either a two-layer wiring, or a three-layer wiring consisting of titanium nitride in the upper layer, aluminum alloy in the middle layer, and high-melting point metals such as titanium, molybdenum, tungsten, tantalum, cobalt, platinum, and silicide compounds thereof in the lower layer. A semiconductor device characterized by: